Most televisions today are based on display technologies that suffer from a problem known as “burn-in”, which is damage to the display from long-persisting static images. The result of burn-in is an undesirable afterimage which can be seen if the set is turned off and/or while a flat color is being displayed. This problem is traditionally addressed in computers by using a “screen saver,” which either modifies the screen to use colors or intensities which are less likely to cause burn-in, or changes the display entirely to a display designed to age the screen uniformly so that no burn-in pattern is visible. Such screen savers are typically triggered by inactivity, i.e., a lack of user input from the keyboard or mouse. However, since television is typically a passive experience, it is common for the television controls not to be touched for long periods of time. As such, an inactivity-based screen saver trigger such as used in computers is generally not appropriate for televisions.
There are various known approaches to solving the burn-in problem for televisions. These are continuous approaches where no “screen saver” function is triggered to prevent the burn-in problem. One such approach is “picture rotation,” where the entire picture is shifted slightly up, down, left, or right of center over time. This technique would cause any sharp transitions on the screen, where burn-in may be more noticeable, to be blurred. However, it does not eliminate the effects of burn-in.
Another technique is to change the brightness of sidebars to match the average brightness of the screen. This technique avoids a distinctive burn-in pattern between the center of the screen and the sidebars. However, since the sidebars represent a stationary, non-changing pattern that can remain on the screen for thousands of hours during the normal course of watching television programs, burn-in still eventually occurs.